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LS1 Body Control Module Problems - The Fix
01-24-2017, 06:59 PM
#362
Staging Lane
Join Date: Feb 2004
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So troubleshooting and fixing some unrelated problems with newly installed LEDs yesterday, I noticed that my door locks periodically don't work. After installing all the new LEDs I checked everything, including door locks using remote and both door switches. All good. Went into the house, came out about an hour later, checked everything again. Remote worked fine but both door switches would only lock the doors and not unlock them. I pulled the driver's side lock/unlock switch out of the armrest and fiddled with it a few minutes and then they started working again.
Another time, later the same evening the driver door switch stopped unlocking the doors but the passenger switch worked fine. Fiddling with the switch in the driver's door it eventually started working. Might be one of the wires connected to the switch, will have to inspect them in better light BUT, I had jiggled all 3 wires multiple times before it suddenly started working again.
Could this be a BCM problem instead?
Another time, later the same evening the driver door switch stopped unlocking the doors but the passenger switch worked fine. Fiddling with the switch in the driver's door it eventually started working. Might be one of the wires connected to the switch, will have to inspect them in better light BUT, I had jiggled all 3 wires multiple times before it suddenly started working again.
Could this be a BCM problem instead?
01-24-2017, 08:37 PM
#363
So troubleshooting and fixing some unrelated problems with newly installed LEDs yesterday, I noticed that my door locks periodically don't work. After installing all the new LEDs I checked everything, including door locks using remote and both door switches. All good. Went into the house, came out about an hour later, checked everything again. Remote worked fine but both door switches would only lock the doors and not unlock them. I pulled the driver's side lock/unlock switch out of the armrest and fiddled with it a few minutes and then they started working again.
Another time, later the same evening the driver door switch stopped unlocking the doors but the passenger switch worked fine. Fiddling with the switch in the driver's door it eventually started working. Might be one of the wires connected to the switch, will have to inspect them in better light BUT, I had jiggled all 3 wires multiple times before it suddenly started working again.
Could this be a BCM problem instead?
Another time, later the same evening the driver door switch stopped unlocking the doors but the passenger switch worked fine. Fiddling with the switch in the driver's door it eventually started working. Might be one of the wires connected to the switch, will have to inspect them in better light BUT, I had jiggled all 3 wires multiple times before it suddenly started working again.
Could this be a BCM problem instead?
With the jiggling of the wires (and Im not sure where you jiggled them near) it could be the connector from the harness into the actual female socket that plugs into the switch.
05-12-2017, 09:57 PM
#364
Not sure if this is the right thread. But both of my power mirrors on on my 93 formula dont work.
I got the car a week ago and the previous owner thought water got into the switch. I bought a used one off ebay and no change. As far as I know, fuse this runs through is shared by other components, and everything else works fine. And it would seem odd for both mirror motors to be dead.
So if its not a bad fuse, bad switch, or bad motors, whats left to check?
I got the car a week ago and the previous owner thought water got into the switch. I bought a used one off ebay and no change. As far as I know, fuse this runs through is shared by other components, and everything else works fine. And it would seem odd for both mirror motors to be dead.
So if its not a bad fuse, bad switch, or bad motors, whats left to check?
10-23-2017, 05:42 PM
#366
Teching In
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Thanks... Been putting up with the radio/windows cutting off for a second or two and coming right back for a couple months, started right after changing my LCA's.
Cold solder joint on 2 of the 5 relay connections. Woo Fn Hoo.
This thread saved me a lot of aggravation and time trouble-shooting this. Thanks much.
Cold solder joint on 2 of the 5 relay connections. Woo Fn Hoo.
This thread saved me a lot of aggravation and time trouble-shooting this. Thanks much.
12-13-2017, 05:03 PM
#367
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Read this entire thread as well as others.
I have both a solid Security light and Radio/Windows/RAP cutting out. I want to say they both started about the same time. So I'm thinking of just replacing the BCM. I'm more concerned with the solid Security light and from what I gather could be related to the BCM??
Car starts and runs fine. Occasionally I have to hold the ignition a tad longer and the car starts right up.
I have both a solid Security light and Radio/Windows/RAP cutting out. I want to say they both started about the same time. So I'm thinking of just replacing the BCM. I'm more concerned with the solid Security light and from what I gather could be related to the BCM??
Car starts and runs fine. Occasionally I have to hold the ignition a tad longer and the car starts right up.
12-14-2017, 08:18 AM
#368
The RAP cutout is what this thread is about. Either the solder fix or replacing the BCM will solve that problem. The VATS security light in the dash is controlled by the BCM but it is very unlikely that the BCM is causing that problem so replacing it probably won't fix that problem.
VATS is intended to help prevent vehicle theft by checking that it sees the expected resistance value of the chip on the original ignition key before allowing the vehicle to start. If it sees a resistance value that is not correct, it illuminates the security light solidly. If it doesn't see any resistance value (because of a damaged or missing resistor pellet in the key or broken wires), it flashes the security light.
If the BCM detects the problem while the car is running, it will assume that there is a system fault rather than a theft attempt and it will allow the car to be restarted. But if it first detects the problem while trying to start the car then it will prevent starting by disabling the starter relay and turning off the fuel enable signal to the PCM. In this case that means that you will continue to be able to start the car until you reset it by disconnecting the battery (for service or replacement). After that, the car will not start.
There are a variety of things that can cause VATS to see the wrong resistor value. The easiest to fix is a simple build-up of grime on the key and in the ignition cylinder. Clean the contacts on the key using a pencil eraser followed by rubbing alcohol. Clean the ignition cylinder with spray electronics cleaner and a pipe cleaner. Other causes include worn contacts on the key or in the cylinder, a damaged cylinder, or broken wires in the steering column or between the column and the BCM.
If a thorough cleaning doesn't solve the problem then you may find that a VATS bypass would be easier than trying to track down the cause. VATS cannot be programmed out in an F-body but a bypass is fairly simple to implement. Search the forum for "VATS bypass" to find plenty of information on how to do it.
VATS is intended to help prevent vehicle theft by checking that it sees the expected resistance value of the chip on the original ignition key before allowing the vehicle to start. If it sees a resistance value that is not correct, it illuminates the security light solidly. If it doesn't see any resistance value (because of a damaged or missing resistor pellet in the key or broken wires), it flashes the security light.
If the BCM detects the problem while the car is running, it will assume that there is a system fault rather than a theft attempt and it will allow the car to be restarted. But if it first detects the problem while trying to start the car then it will prevent starting by disabling the starter relay and turning off the fuel enable signal to the PCM. In this case that means that you will continue to be able to start the car until you reset it by disconnecting the battery (for service or replacement). After that, the car will not start.
There are a variety of things that can cause VATS to see the wrong resistor value. The easiest to fix is a simple build-up of grime on the key and in the ignition cylinder. Clean the contacts on the key using a pencil eraser followed by rubbing alcohol. Clean the ignition cylinder with spray electronics cleaner and a pipe cleaner. Other causes include worn contacts on the key or in the cylinder, a damaged cylinder, or broken wires in the steering column or between the column and the BCM.
If a thorough cleaning doesn't solve the problem then you may find that a VATS bypass would be easier than trying to track down the cause. VATS cannot be programmed out in an F-body but a bypass is fairly simple to implement. Search the forum for "VATS bypass" to find plenty of information on how to do it.
Last edited by WhiteBird00; 12-15-2017 at 07:03 AM. Reason: fix run-on sentences
12-14-2017, 05:46 PM
#370
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The RAP cutout is what this thread is about. Either the solder fix or replacing the BCM will solve that problem. The VATS security light in the dash is controlled by the BCM but it is very unlikely that the BCM is causing that problem so replacing it probably won't fix that problem.
VATS is intended to help prevent vehicle theft by checking that it sees the expected resistance value of the chip on the original ignition key before allowing the vehicle to start. If it sees a resistance value that is not correct, it illuminates the security light solidly. If it doesn't see any resistance value (because of a damaged or missing resistor pellet in the key or broken wires), it flashes the security light.
If the BCM detects the problem while the car is running, it will assume that there is a system fault rather than a theft attempt and it will allow the car to be restarted but if it first detects the problem while trying to start the car then it will prevent starting by disabling the starter relay and turning off the fuel enable signal to the PCM. In this case that means that you will continue to be able to start the car until you reset it by disconnecting the battery (for service or replacement). After that, the car will not start.
There are a variety of things that can cause VATS to see the wrong resistor value. The easiest to fix is a simple build-up of grime on the key and in the ignition cylinder. Clean the contacts on the key using a pencil eraser followed by rubbing alcohol. Clean the ignition cylinder with spray electronics cleaner and a pipe cleaner. Other causes include worn contacts on the key or in the cylinder, a damaged cylinder, broken wires in the steering column or between the column and the BCM.
If a thorough cleaning doesn't solve the problem then you may find that a VATS bypass would be easier than trying to track down the cause. VATS cannot be programmed out in an F-body but a bypass is fairly simple to implement. Search the forum for "VATS bypass" to find plenty of information on how to do it.
VATS is intended to help prevent vehicle theft by checking that it sees the expected resistance value of the chip on the original ignition key before allowing the vehicle to start. If it sees a resistance value that is not correct, it illuminates the security light solidly. If it doesn't see any resistance value (because of a damaged or missing resistor pellet in the key or broken wires), it flashes the security light.
If the BCM detects the problem while the car is running, it will assume that there is a system fault rather than a theft attempt and it will allow the car to be restarted but if it first detects the problem while trying to start the car then it will prevent starting by disabling the starter relay and turning off the fuel enable signal to the PCM. In this case that means that you will continue to be able to start the car until you reset it by disconnecting the battery (for service or replacement). After that, the car will not start.
There are a variety of things that can cause VATS to see the wrong resistor value. The easiest to fix is a simple build-up of grime on the key and in the ignition cylinder. Clean the contacts on the key using a pencil eraser followed by rubbing alcohol. Clean the ignition cylinder with spray electronics cleaner and a pipe cleaner. Other causes include worn contacts on the key or in the cylinder, a damaged cylinder, broken wires in the steering column or between the column and the BCM.
If a thorough cleaning doesn't solve the problem then you may find that a VATS bypass would be easier than trying to track down the cause. VATS cannot be programmed out in an F-body but a bypass is fairly simple to implement. Search the forum for "VATS bypass" to find plenty of information on how to do it.
12-26-2017, 02:13 PM
#371
Staging Lane
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Bcm 99 z28 The radio and windows on my 99 Z28 do go out intermittently however if I smack the dashboard the radio will come back on. This does not sound like a bad soldering on the circuit board to me. Anybody care to advise me on this? I would not attempt a soldering fix and do not want to get robbed by a repair from the Dealer but I would try to disconnect and re-connect the wires if someone could tell me how to do that. I like to start with the least expensive fix first. I am not a car DIYer. Thanks for any help with this.
12-26-2017, 06:42 PM
#372
TECH Fanatic
The radio and windows on my 99 Z28 do go out intermittently however if I smack the dashboard the radio will come back on. This does not sound like a bad soldering on the circuit board to me. Anybody care to advise me on this? I would not attempt a soldering fix and do not want to get robbed by a repair from the Dealer but I would try to disconnect and re-connect the wires if someone could tell me how to do that. I like to start with the least expensive fix first. I am not a car DIYer. Thanks for any help with this.
12-29-2017, 07:15 AM
#374
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Not sure which Forum this should be under so please feel free to move this and delete this sentence.
I've had 3 LS1 cars over the past few years that had intermitent body control module problems. When your radio and power windows intermitently go on and off, it's a body control module problem. This must be somewhat common and most people probably don't know where the problem lies.
Today I took a shot at trying to fix the module itself as buying a new one is around $200. You can buy a used one but then you have to know the VIN of the car it came out of so you can get the VATS code and make a new ignition key for your car that matches the used BCM.
The BCM is located on the passenger side under the dash just behind the glove box. To my surprise, the entire circuit board is just sitting inside a black plastic box that unsnaps. Unsnap the box and remove the entire circuit board. I was able to isolate the problem to the main power circuit/plug-in. After playing the wiggle-parts game, I found that the relay just behind the plug was the problem. There are 5 solder joints holding the relay onto the board. One solder joint looked like it had a super tiny micro-crack in it. I heated that one solder joint and added some additional solder and whaddayaknow !!!! it fixed it ! Your mileage may vary but I would reheat each of the 5 solder joints.
Here is a picture of the circuit board with the 5 solder joints crudely circled. The bottom joint was my problem.
Just thought you guys would like to see this.
Greg Crowe
http://www.camarofirebird.com
I've had 3 LS1 cars over the past few years that had intermitent body control module problems. When your radio and power windows intermitently go on and off, it's a body control module problem. This must be somewhat common and most people probably don't know where the problem lies.
Today I took a shot at trying to fix the module itself as buying a new one is around $200. You can buy a used one but then you have to know the VIN of the car it came out of so you can get the VATS code and make a new ignition key for your car that matches the used BCM.
The BCM is located on the passenger side under the dash just behind the glove box. To my surprise, the entire circuit board is just sitting inside a black plastic box that unsnaps. Unsnap the box and remove the entire circuit board. I was able to isolate the problem to the main power circuit/plug-in. After playing the wiggle-parts game, I found that the relay just behind the plug was the problem. There are 5 solder joints holding the relay onto the board. One solder joint looked like it had a super tiny micro-crack in it. I heated that one solder joint and added some additional solder and whaddayaknow !!!! it fixed it ! Your mileage may vary but I would reheat each of the 5 solder joints.
Here is a picture of the circuit board with the 5 solder joints crudely circled. The bottom joint was my problem.
Just thought you guys would like to see this.
Greg Crowe
http://www.camarofirebird.com
12-29-2017, 07:19 AM
#375
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Not sure which Forum this should be under so please feel free to move this and delete this sentence.
I've had 3 LS1 cars over the past few years that had intermitent body control module problems. When your radio and power windows intermitently go on and off, it's a body control module problem. This must be somewhat common and most people probably don't know where the problem lies.
Today I took a shot at trying to fix the module itself as buying a new one is around $200. You can buy a used one but then you have to know the VIN of the car it came out of so you can get the VATS code and make a new ignition key for your car that matches the used BCM.
The BCM is located on the passenger side under the dash just behind the glove box. To my surprise, the entire circuit board is just sitting inside a black plastic box that unsnaps. Unsnap the box and remove the entire circuit board. I was able to isolate the problem to the main power circuit/plug-in. After playing the wiggle-parts game, I found that the relay just behind the plug was the problem. There are 5 solder joints holding the relay onto the board. One solder joint looked like it had a super tiny micro-crack in it. I heated that one solder joint and added some additional solder and whaddayaknow !!!! it fixed it ! Your mileage may vary but I would reheat each of the 5 solder joints.
Here is a picture of the circuit board with the 5 solder joints crudely circled. The bottom joint was my problem.
Just thought you guys would like to see this.
Greg Crowe
http://www.camarofirebird.com
I've had 3 LS1 cars over the past few years that had intermitent body control module problems. When your radio and power windows intermitently go on and off, it's a body control module problem. This must be somewhat common and most people probably don't know where the problem lies.
Today I took a shot at trying to fix the module itself as buying a new one is around $200. You can buy a used one but then you have to know the VIN of the car it came out of so you can get the VATS code and make a new ignition key for your car that matches the used BCM.
The BCM is located on the passenger side under the dash just behind the glove box. To my surprise, the entire circuit board is just sitting inside a black plastic box that unsnaps. Unsnap the box and remove the entire circuit board. I was able to isolate the problem to the main power circuit/plug-in. After playing the wiggle-parts game, I found that the relay just behind the plug was the problem. There are 5 solder joints holding the relay onto the board. One solder joint looked like it had a super tiny micro-crack in it. I heated that one solder joint and added some additional solder and whaddayaknow !!!! it fixed it ! Your mileage may vary but I would reheat each of the 5 solder joints.
Here is a picture of the circuit board with the 5 solder joints crudely circled. The bottom joint was my problem.
Just thought you guys would like to see this.
Greg Crowe
http://www.camarofirebird.com
